Network Working Group T. Howes
Request for Comments: 1959 M. Smith
Category: Standards Track University of Michigan
June 1996
An LDAP URL Format
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
1. Abstract
LDAP is the Lightweight Directory Access Protocol, defined in [1] and
[2]. This document describes a format for an LDAP Uniform Resource
Locator which will allow Internet clients to have direct access to
the LDAP protocol. While LDAP currently is used only as a front end
to the X.500 directory, the URL format described here is general
enough to handle the case of stand-alone LDAP servers (i.e., LDAP
servers not back-ended by X.500).
2. URL Definition
An LDAP URL begins with the protocol prefix "ldap" and is defined by
the following grammar.
<ldapurl> ::= "ldap://" [ <hostport> ] "/" <dn> [ "?" <attributes>
[ "?" <scope> "?" <filter> ] ]
<hostport> ::= <hostname> [ ":" <portnumber> ]
<dn> ::= a string as defined in RFC 1485
<attributes> ::= NULL | <attributelist>
<attributelist> ::= <attributetype>
| <attributetype> [ "," <attributelist> ]
<attributetype> ::= a string as defined in RFC 1777
<scope> ::= "base" | "one" | "sub"
<filter> ::= a string as defined in RFC 1558
Howes & Smith Standards Track [Page 1]RFC 1959 An LDAP URL Format June 1996
The ldap prefix indicates an entry or entries residing in the LDAP
server running on the given <hostname> at the given <portnumber>.
The default port is TCP port 389. The <dn> is an LDAP Distinguished
Name using the string format described in [1], with any URL-illegal
characters (e.g., spaces) escaped using the % method described in RFC
1738.
The <attributes> construct is used to indicate which attributes
should be returned from the entry or entries. Individual
<attributetype> names are as defined for AttributeType in RFC 1777.
If the <attributes> part is omitted, all attributes of the entry or
entries should be returned.
The <scope> construct is used to specify the scope of the search to
perform in the given LDAP server. The allowable scopes are "base"
for a base object search, "one" for a one-level search, or "sub" for
a subtree search. If <scope> is omitted, a scope of "base" is
assumed.
The <filter> is used to specify the search filter to apply to entries
within the specified scope during the search. It has the format
specified in [4], with any URL-illegal characters escaped using the %
method described in RFC 1738. If <filter> is omitted, a filter of
"(objectClass=*)" is assumed.
Note that if the entry resides in the X.500 namespace, it should be
reachable from any LDAP server that is providing front-end access to
the X.500 directory. If the <hostport> part of the URL is missing,
the URL can be resolved by contacting any X.500-back-ended LDAP
server.
3. Examples
The following are some example LDAP URLs using the format defined
above. An LDAP URL referring to the University of Michigan entry,
available from any X.500-capable LDAP server:
ldap:///o=University%20of%20Michigan,c=US
An LDAP URL referring to the University of Michigan entry in a
particular ldap server:
ldap://ldap.itd.umich.edu/o=University%20of%20Michigan,c=US
This URL corresponds to a base object search of the "o=University of
Michigan, c=US" entry using a filter of (objectclass=*), requesting
all attributes.
Howes & Smith Standards Track [Page 2]RFC 1959 An LDAP URL Format June 1996
An LDAP URL referring to only the postalAddress attribute of the
University of Michigan entry:
ldap://ldap.itd.umich.edu/o=University%20of%20Michigan,c=US?postalAddress
The corresponding LDAP search operation is the same as in the
previous example, except that only the postalAddress attribute is
requested.
An LDAP URL referring to the set of entries found by querying any
X.500-capable LDAP server and doing a subtree search of the
University of Michigan for any entry with a common name of "Babs
Jensen", retrieving all attributes:
ldap:///o=University%20of%20Michigan,c=US??sub?(cn=Babs%20Jensen)
An LDAP URL referring to all children of the c=GB entry:
ldap://ldap.itd.umich.edu/c=GB?objectClass?one